1. Field of the Invention
The present disclosed technology relates generally to a hub for a wheel. More specifically, the invention provides a wheel hub for use on a wheel in high rotational speed and high torque applications.
2. Description of the Related Art
Wheels used on vehicles subject to high rotational speed and high torque environments, such as sprint racecars, require special wheels that are light weight, strong, and capable of withstanding the harsh racing environment. Racecar builders desire to increase the efficiency of their racecars by decreasing the overall weight of the racecar. It is well known in the automotive industry that components which rotate increase the dynamic load on the racecar, and require more kinetic energy (i.e. horsepower) to rotate those components and move the vehicle. Racecar and engine builders call this kinetic energy the angular moment of inertia or “rotating weight.” One such component having rotating weight is the wheel. The wheel may include a central hub and rim, all of which are rotatively connected to the drive shaft of the racecar engine. In high speed and high torque applications, the wheel experiences high rotational speed coupled with a large down force. The wheel must have sufficient strength to withstand this harsh environment.
Wheels incapable of withstanding the harsh racing environment suffer structural failures that often result in damage to the vehicle as well as damage to surrounding structures or bystanders. An example of such a harsh racing environment may include the racing conditions often experienced in sprint car racing, midget car racing, and other dirt track racing environments. As such, wheels used in the aforementioned applications must be of sufficient strength to withstand the impact of other vehicles, and impact with the racetrack barrier, which may vary from an energy absorbing “soft wall,” to concrete.
One approach to the design of high strength and lightweight wheels utilizes a hub mechanically fastened to a rim shell. The separate hub and rim configuration allows for the rim shell to be replaced in the event of damage, such as the wheel striking another vehicle, obstacle, or racetrack barrier. This design configuration also provides options for various hub designs to be fastened to a standard rim shell, and for minimizing the weight of the wheel.
The weight or mass of a rotating wheel about an axis may be described in terms of its moment of inertia, which is expressed by the equation: Iaxis=½(mass×radius2), where “I” is the moment of inertia at the axis of rotation, “mass” is the mass of the rotating wheel, and “radius” is the distance from the axis of rotation to the edge of the wheel. Hence, the lower the mass of the wheel, the lower the moment of inertia of the rotating wheel. As seen in the equation above, the most efficient method of reducing the rotational moment of inertia is to decrease the radius (i.e., diameter) of the wheel. This may not be an option for some racing applications in which the sanctioning body specifies a diameter, or a range of diameters, of the wheels that may be used. In addition, decreasing the diameter of the wheel may have other disadvantages in applications that rely on the front wheels of the race car to break a photoelectric beam passing in front of the racecar, such as the beam used to count laps or track racing time. As such, a large diameter wheel traveling the same linear speed as a smaller diameter wheel will break the photoelectric beam before a smaller diameter wheel.
An alternative approach to reducing the moment of inertia of a wheel is to decrease the mass of the wheel. Various methods may be used to reduce the mass of the wheel, such as by material selection, reducing the thickness of the wheel components, or removing material from the wheel rim or hub that is not structurally needed. However, decreasing the mass of the wheel requires careful structural analysis of the wheel, the effect it will have on the strength of the wheel, and its ability to withstand racing conditions.
Therefore, there is a need for a wheel hub that has a reduced mass or moment of inertia, and the structural strength necessary for racing or high performance vehicle applications. Heretofore there has not been available a wheel hub with the features and advantages of the disclosed subject matter.